Consider java for fixing this code please:

what i need is to insert method to be added ( please don't change the test class and any giving value in the first class )

here is the correct out put:

------------------testAddLast()----

{A}

{A->B}

{A->B->null}

{A->B->null->C}

-----------------------------

--------testSubListOfSmallerValues()----------

{}

{B->B->B->A}

{F->B->B->B->A->D}

{F->B->B->G->B->A->M->D}

-----------------------------

------------Test lastIndexOf()-----

-1

3

-1

-1

0

5

2

-----------------------------

---------testRetainAll()---------

{}

{6:Tony->6:Tony}

{null->bad->null}

-----------------------------

---------------Test removeStartingAtBack---

false

true

{apple->null->bad->null}

true

{apple->null->bad}

{2:Morning->3:Abby->4:Tim->5:Tom->6:Tony}

-----------------------------

---------test insertionSort()---------

{}

{D}

{D->E->E->F->G}

-----------------------------

the code is here:

/* NOTE: PLEASE DO NOT CHANGE OR REVISE ANY CODE IN THIS TESTER */ /* !!! IF YOU CHANGE THIS FILE, YOU GET A ZERO FOR THIS PROJECT !!!! */ class CDoublyLinkedList { private class Node { private Object data; // Assume data implemented Comparable private Node next, prev; private Node(Object data, Node pref, Node next) { this.data = data; this.prev = pref; this.next = next; } } private Node head; private int size; public CDoublyLinkedList() { this.head = new Node(null, null, null); this.head.next = this.head; this.head.prev = this.head; this.size = 0; } public boolean isEmpty() { return this.head == this.head.next; } // Add Object data to start of this LinkedList // Please DO NOT change this addFirst() method. public void addFirst(Object data) { Node nn = new Node(data, this.head, this.head.next); this.head.next.prev = nn; this.head.next = nn; this.size++; } // write a method void addLast(Object data) that will insert // the piece of data at the end of the current list. // Note: this list is allowed to store null data element in its list node. public void addLast(Object data) { Node nn = new Node(data, this.head.prev, this.head); this.head.prev.next = nn; this.head.prev = nn; this.size++; } // Write the subListOfSmallerValues method. // It should return a CDoublyLinkedList object // containing data that is smaller than the value passed to the method. // If a null data element in this list is encountered, you can skip it. public CDoublyLinkedList subListOfSmallerValues(Comparable data) { CDoublyLinkedList result = new CDoublyLinkedList(); Node start = head.next; while (start != head) { if (start.data != null && data.compareTo(start.data) > 0) { result.addLast(start.data); } start = start.next; } return result; // change this as needed. } // This method should remove the first occurrence of the data from the list, // starting at the *BACK* of the list. // It scans the list from back to the front by following the prev links. // The method should return true if successful, false otherwise. // Note that list node may contain null data element. Please handle this edge // case. public boolean removeStartingAtBack(Object dataToRemove) { Node start = head.prev; while (start != head) { if ((start.data == null && dataToRemove == null) || (start.data != null && dataToRemove.equals(start.data))) { start.prev.next = start.next; start.next.prev = start.prev; size--; return true; } start = start.prev; } return false;// change this as needed. } // Returns the index of the last occurrence of the specified element in this // list, // or -1 if this list does not contain the element. // More formally, returns the highest index i // such that (o==null ? get(i)==null : o.equals(get(i))), // or -1 if there is no such index. // Note: a list node may store a null data element. Please handle this edge // case. public int lastIndexOf(Object o) { int index = -1; int i = 0; Node start = head.next; while (start != head) { if ((start.data == null && o == null) || (start.data != null && start.data.equals(o))) { index = i; } start = start.next; i++; } return index; // change this as needed. } // Removes from this list all of its elements that // are NOT contained in the specified linkedlist other. // If any element has been removed from this list, // returns true. Otherwise returns false. // If other list is null, throws NullPointerException. // Helper methods are allowed. public boolean retainAll(CDoublyLinkedList other) throws NullPointerException { if (other == null) { throw new NullPointerException(); } boolean status = false; Node start = head.prev; while (start != head) { if (other.lastIndexOf(start.data) == -1) { Object x = start.data; start = start.prev; removeStartingAtBack(x); status = true; } else { start = start.prev; } } return status; // change this as needed. } // a comes before, b comes later. private void swapNodes(Node a, Node b) { Node prev1 = a.prev; Node next1 = a.next; Node prev2 = b.prev; Node next2 = b.next; a.next = next2; a.prev = prev2; b.next = next1; b.prev = prev1; prev1.next = b; next1.prev = b; prev2.next = a; next2.prev = a; } // Write this method to sort this list using insertion sort algorithm, // as we have learned in the classroom. public void insertionSort() { } @Override public String toString() { String result = "{"; for (Node node = this.head.next; node != this.head; node = node.next) { if (node.next != this.head) result += node.data + "->"; else result += node.data; } return result + "}"; } } public class Tester { private static CDoublyLinkedList list0; private static CDoublyLinkedList list2; private static CDoublyLinkedList list3; private static void init() { list0 = new CDoublyLinkedList(); list2 = new CDoublyLinkedList(); list3 = new CDoublyLinkedList(); list2.addFirst("6:Tony"); list2.addFirst("5:Tom"); list2.addFirst("4:Tim"); list2.addFirst("3:Abby"); list2.addFirst("2:Morning"); list2.addFirst("1:Good"); list0.addFirst(null); list0.addFirst("bad"); list0.addFirst("apple"); list0.addFirst(null); } public static void drawLine() { System.out.println("-----------------------------"); } public static void testAddFirst() { // passed test init(); drawLine(); System.out.println(list0); System.out.println(list2); System.out.println(list3); drawLine(); } public static void testAddLast() { // System.out.println("------------------testAddLast()----"); init(); list3.addLast("A"); System.out.println(list3); list3.addLast("B"); System.out.println(list3); list3.addLast(null); System.out.println(list3); list3.addLast("C"); System.out.println(list3); drawLine(); } public static void testRemoveStartingAtBack() { init(); System.out.println("---------------Test removeStartingAtBack---"); list0.addFirst("apple"); System.out.println(list0.removeStartingAtBack("notexist")); // false System.out.println(list0.removeStartingAtBack("apple")); // true System.out.println(list0); // apple, null, bad, null System.out.println(list0.removeStartingAtBack(null)); // true System.out.println(list0); // apple, null, bad list2.removeStartingAtBack("1:Good"); System.out.println(list2); drawLine(); } public static void testLastIndexOf() { init(); System.out.println("------------Test lastIndexOf()-----"); System.out.println(list3.lastIndexOf("notexist")); // -1 System.out.println(list0.lastIndexOf(null)); // 3 System.out.println(list2.lastIndexOf(null)); // -1 System.out.println(list2.lastIndexOf("notexist"));// -1 System.out.println(list2.lastIndexOf("1:Good"));// 0 System.out.println(list2.lastIndexOf("6:Tony"));// 5 list3.addFirst("B3"); list3.addFirst("B3"); list3.addFirst("B3"); System.out.println(list3.lastIndexOf("B3"));// 2 drawLine(); } public static void testSubList() { init(); list3.addFirst("D"); list3.addFirst("M"); list3.addFirst("A"); list3.addFirst("B"); list3.addFirst("G"); list3.addFirst("B"); list3.addFirst("B"); list3.addFirst("F"); System.out.println("--------testSubListOfSmallerValues()----------"); System.out.println(list3.subListOfSmallerValues("A")); // none System.out.println(list3.subListOfSmallerValues("C")); // BBBA System.out.println(list3.subListOfSmallerValues("G")); // FBBBAD System.out.println(list3.subListOfSmallerValues("Q")); // FBBGBAMD drawLine(); } public static void testRetainAll() { init(); System.out.println("---------testRetainAll()---------"); list3.retainAll(list0); System.out.println(list3); list3.addFirst("C"); list3.addFirst("C"); list3.addFirst("6:Tony"); list3.addFirst("6:Tony"); list3.retainAll(list2); System.out.println(list3); init(); list3.addFirst(null); list3.addFirst("bad"); list3.addFirst(null); list3.addFirst("B"); list3.addFirst("A"); list3.retainAll(list0); System.out.println(list3); drawLine(); } public static void testSort() { init(); System.out.println("---------test insertionSort()---------"); list3.insertionSort(); System.out.println(list3); // none list3.addFirst("D"); System.out.println(list3); // D list3.addFirst("F"); list3.addFirst("E"); list3.addFirst("G"); list3.addFirst("E"); list3.insertionSort(); System.out.println(list3); // DEEFG drawLine(); } public static void main(String argv[]) { testAddLast(); testSubList(); testLastIndexOf(); testRetainAll(); testRemoveStartingAtBack(); testSort(); }// end of main }